I would stop right away, you need to make sure it's the correct insulation otherwise you are going to have major problems in the future. You also need to get it signed off my building control so both the water repellent and the thermal performance must be suitable.
I agree it does look like wood fiber which is normally given a water proof finish or used internally.
Try secondsandco for cheap kingspan. Also check with your building control officer as to how he wants the wall made up. It's not just a case of "full fill a cavity with insulation" - all needs to be specific for the job, air gaps as specified (and to be effective as insulation, it needs to be fixed in a particular way)
In terms of insulating afterwards, brick ties make that a really hard thing to do unless it's a blown in product...
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